<?php
// +----------------------------------------------------------------------
// | Yzncms [ 御宅男工作室 ]
// +----------------------------------------------------------------------
// | Copyright (c) 2007 http://yzncms.com All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: 御宅男 <530765310@qq.com>
// +----------------------------------------------------------------------

/**
 * 系统非常规MD5加密方法
 * @param  string $str 要加密的字符串
 * @return string
 */
function think_ucenter_md5($str, $key = 'ThinkUCenter')
{
    return '' === $str ? '' : md5(sha1($str) . $key);
}

/**
 * 系统加密方法
 * @param string $data 要加密的字符串
 * @param string $key  加密密钥
 * @param int $expire  过期时间 (单位:秒)
 * @return string
 */
function think_ucenter_encrypt($data, $key, $expire = 0)
{
    $key = md5($key);
    $data = base64_encode($data);
    $x = 0;
    $len = strlen($data);
    $l = strlen($key);
    $char = '';
    for ($i = 0; $i < $len; $i++) {
        if ($x == $l) {
            $x = 0;
        }

        $char .= substr($key, $x, 1);
        $x++;
    }
    $str = sprintf('%010d', $expire ? $expire + time() : 0);
    for ($i = 0; $i < $len; $i++) {
        $str .= chr(ord(substr($data, $i, 1)) + (ord(substr($char, $i, 1))) % 256);
    }
    return str_replace('=', '', base64_encode($str));
}

/**
 * 系统解密方法
 * @param string $data 要解密的字符串 （必须是think_encrypt方法加密的字符串）
 * @param string $key  加密密钥
 * @return string
 */
function think_ucenter_decrypt($data, $key)
{
    $key = md5($key);
    $x = 0;
    $data = base64_decode($data);
    $expire = substr($data, 0, 10);
    $data = substr($data, 10);
    if ($expire > 0 && $expire < time()) {
        return '';
    }
    $len = strlen($data);
    $l = strlen($key);
    $char = $str = '';
    for ($i = 0; $i < $len; $i++) {
        if ($x == $l) {
            $x = 0;
        }

        $char .= substr($key, $x, 1);
        $x++;
    }
    for ($i = 0; $i < $len; $i++) {
        if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1))) {
            $str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));
        } else {
            $str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));
        }
    }
    return base64_decode($str);
}
